Conventional knee pads are available in two types: soft shell and hard shell. Volleyball players, for example, use soft knee pads that attach with elastic straps. Hard shell knee pads generally include a soft inner pad fixed to a hard outer pad of material having a higher density (i.e., the hard shell). Like the soft shell knee pads, the most hard shell knee pads are attachable to the wearer using elastic straps. If the straps are permanently attached to the knee pad system then it is worn by sliding it over the foot and up to the knee. Otherwise, the straps may be attached using clips, buckles or a hook-and-loop fastening system (e.g., a VELCRO® fastening system). The pads may be worn under or over pants.
After so much movement like walking or running, the strap-style knee pads often begin to fall or at least move with respect to the knee, thus requiring effort to pull the knee pad back up or to adequately reposition it. In some environments such as a military combat situation, a soldier's split second movement to pull up his knee pad could give away his position or provoke even harsher consequences. In other, less dangerous, environments the pulling up or repositioning of strap-style knee pads can just be irritating. Protective pads that are not in the proper place may also not provide adequate protection. The pads and straps can also bind or chafe the knee or leg making the pads uncomfortable to wear.
One type of knee pad system provides for the knee pad to be sewn into the apparel, which essentially results in a non-removable knee pad. One drawback of such a permanent assembly is that in many activities the wearer may perspire, which in turn generates moisture that is absorbed by the knee pad. The moist knee pad may then become heavier and less comfortable. Closed-cell pads have been developed for use with pants and may be insertable into a knee pocket in the pants. However, these pads do not prevent excessive wear on the outer layer of the pants and may even accelerate the wear of the pant knees.
These same basic considerations apply to elbow pads, hip pads, and other protective pads.